Spherical pumps are in many aspects superior to the well known canned pumps that have shaft and bushings rotating in the liquid conveyed. The working clearance within the bushings tends to clog because the friction caused temperature of the liquid conveyed. The working clearance within the bushings tends to clog because the friction caused temperature within the bearing clearance space is higher than the temperature of the liquid conveyed. In addition, scaling, especially from calcium components, will build up in this space. In addition, the leakage flux of the motor runs generally parallel to the clearance within the bushings, attracting ferro-magnetic particles such as rust into the clearance. A large amount of clogging causes seizing, the main reason for failure of canned pumps. The most important advantage of spherical pumps is the fact that they have neither shafts nor bushings. Therefore, seizing within the spherical bearings is considerably less probable; nevertheless, spherical bearings can also seize, caused by ad-mixtures to the fluid conveyed. These ad-mixtures have the tendency to accumulate within the clearance, forming a viscid layer.
The aim of the invention is the prevention of buildups within the bearing clearance that may cause seizing. The invention makes use of a new design of spherical bearings, characterized by grooves with a radial extension exceeding the radius of the ball and mounted between pressure side and suction side of the pump.
Spherical bearings are known. GB No. 2,101,695 shows a spherical bearing with a rotating ball. Around the periphery of said ball are spirally curved grooves 17, causing grease 21 to move from the periphery to the drain hole 8 in the center at the deepest point of the spherical cap 2. As shown by the two arrows, the grease recirculates slowly from the lower level 20 to the upper level 21. A similar design is shown in GB No. 1,212,481 forming a vertically loaded journal bearing for high speed shafts. Here also the shaft 4 with a semi-spherical end 6 rotates in a cap-shaped recess 7 with a bore 10. The oil flows here also from the outer diameter of the semi-spherical end to the nadir of the recess 7 and from there through channel 9 back to the sump. In both bearings the lubricant is driven against the centrifugal forces in the bearing clearance. This flow pattern would not be applicable to fluids containing dirt particles. Dirt particles would accumulate around the inner periphery of the spherical cap.